Salmonella spp. prevalence and antimicrobial resistance pattern (phenotypic profiles and presence of genetic AMR determinants) of serotypes isolated from pet reptiles in Northern Italy

A total of 324 cloacal swabs were collected from reptiles kept at pet animals import centres (48 samples), pet shops (103 samples), zoological park (71 samples) and private owners (102 samples) located in Northern Italy. Samples were collected from healthy snakes (n = 147), lizards (n = 85) and turtles (n = 92). Isolation, typization of Salmonella spp. and the evaluation of sensitivity to different classes of antimicrobial drugs (16 antimicrobial agents) were performed using the classical bacteriological and serological procedures and the agar disc diffusion method (Kirby-Bauer). Isolates showing particular phenotypic AMR profiles were subjected to further molecular characterizations, especially the detection by PCR and sequencing of genetic elements involved in the diffusion and dissemination of AMR among Enterobacteriaceae (i.e. class 1 and class 2 integrons and AMR genes codifying for the resistance to tetracycline, aminoglycosides, beta-lactams, phenicol compounds etc...). Salmonella spp. was isolated from 205 (63.3 %) cloacal swabs. Prevalence data were different for snakes (76.9 %) and lizards (74.1 %) compared to turtles (31.5 %). Serotyping showed the presence of S. enterica subsp. enterica (53.2 %), S. enterica subsp. diarizonae (29.8 %), S. enterica subsp. houtenae (10.2 %), S. enterica subsp. salamae (6.3 %) and S. enterica subsp. arizonae (0.5 %). Out of 205 isolates, only 12 (5.8 %) showed full susceptibility to all the drugs tested and 95 (46.3 %) strains showed multidrug-resistance (i. e. resistance to three or more antimicrobials). Out of the 205 isolates, only 1 carried class 1 integron and only few strains showed a correlation between the phenotypic and genotypic patterns of AMR. These data underlines the importance to carry out further genetic investigations to better understand the genetic bases and mechanisms of the diffusion of AMR among these strains.